Effective January 1, 2009 through until January 1, 2011, state sales taxes do not apply to sales of new passenger cars, light duty trucks, and medium duty passenger vehicles, which utilize hybrid technology and have an EPA estimated highway gasoline mileage rating of at least forty miles per gallon. "Hybrid technology" is defined as propulsion units powered by both electricity and gasoline.
Electric, CNG, and LPG vehicles are exempt from emission control inspections. Effective June 13, 2002, hybrid motor vehicles that obtain a rating by the U.S. Environmental Protection Agency of at least 50 miles per gallon of gas during city driving are also exempt from these inspections.
Can & Should Vehicle Electification be Part of Washington State's Transportation Future?Plug In Hybrid Vehicle report - Feb. 28, 2008
Low Polluting Vehicles and Fleet Issues